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I had a higher than expected OG in my homebrew. It was estimated to come out to 1.060 but instead ended up at 1.076. The back of the yeast I used said that it is good in a brew of up to 1.060 OG. The yeast seems to still be alive and kicking after 12 hours. Should I still be concerned? Is there anything I should do?

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Any other details about the yeast, such as the manufacturer, production/use by date. Did it come with a kit? In general, it should be ok, but there may be exceptions! Can you also confirm you've calibrated your hydrometer, and stirred the wort to ensure it's uniformly mixed, or can some how account for the increase in SG? It may be that the SG is not actually higher, but the measurements are off. –  mdma Jun 24 '13 at 15:05
    
The manufacturer of the yeast is Wyeast, production date was Jun 10th, 2013. The type of yeast is 3068 Weihenstephan. It did not come with a kit. It is liquid yeast. I have not calibrated my hydrometer, how do I do that? I stirred the wort very well and took multiple readings. It consistently came back to 1.076. After 48 hours the fermentation is very vigorous. I had to put in a blow off tube. Does this mean I will need to add additional yeast? If I do, do I need to aerate the wort again when adding the yeast? –  anton2g Jun 25 '13 at 16:24
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There's not much point pitching new yeast after 48h. The flavor contributions from the propagation are now already in the beer. –  mdma Jun 25 '13 at 17:30

2 Answers 2

up vote 3 down vote accepted

You don't need to be excessively concerned now. If the beer really was 1.076, the yeast will multiply to the quantity needed to ferment it - they don't just suddenly stop working when the OG goes above 1.060 - the yeast will still ferment and make beer. However, the multiplication is a stress factor for the yeast and the beer will not be as good as if you had pitched the correct amount of yeast. In future, buy more packs of yeast, or make a starter. This yeast calculator can tell you how much to pitch.

Worse case is that it may end up being slightly sweeter/fuller because of a higher final gravity, or possibly more fruity because of the increased rate of propagation, and maybe some hot alcohol as well from underpitching. But you'll still end up with beer.

To improve your process for future brews, I would try to find out why the beer was at 1.076. Assuming a beer kit with extract, the higher gravity will be either because you added less water than described or the wort wasn't completely mixed when you took a gravity sample, so some parts are thin while others are thick, and you took a reading from the thicker part. Or, if you formulated/made changes to a recipe then use brewing software such as Beersmith, or one of the many online recipe formulators.

It's a good idea to rehydrate dry yeast, especially for bigger beers, since you can lose up to 40% of the yeast cells when direct pitching. But of course, if there are instructions specifically saying to pitch directly then do that, otherwise rehydrate in the sachet in 200ml of hand-warm water and leave for 15 mins, then stir, and leave for a further 15 mins, before pitching.

For liquid yeast, always make a starter, since pitching just the pack/vial is almost always an underpitch. See Always making a starter vs following the package description.

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I'm sorry, but I had to downvote for trhis comment..."the yeast will multiply to the quantity needed to ferment it ". If that's true, why pitch more than oner cell? If you revise the answer, I'll change my vote. –  Denny Conn Jun 25 '13 at 15:54
    
Oh come on - downvote a whole answer because of one statement? That's what the comments are for. This isn't one cell - it's 200 billion. And, even from 1 cell the yeast will eventually multiply but it will just take too long. The case here, an underpitch by 25%, is easily made up by just a quarter of the yeast propagating, which will take 3-8 hours. Most people underpitch by way more than this when pitching a vial/smackpack directly and they make acceptable beer. My statement is correct - the yeast will multiply, and consistent with a slight underpitch there may be more esters. –  mdma Jun 25 '13 at 15:57
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I've under-pitched more times than I care to mention, and every time I ended up with drinkable beer. Pitching the correct number of cells is desirable for complete attenuation, lowered quantities of esters and phenols, shorter lag, etc. But, as @mdma points out, the beer will still ferment. –  Tobias Patton Jun 25 '13 at 16:05
    
Would it be beneficial to pitch more yeast now, or should I just ride it out? Just as an FYI, I used a smackpack with 100 billion cells. And I did stir the wort with the water before taking multiple readings. I went off a recipe from homebrewtalk: homebrewtalk.com/f70/arkadors-dunkelweizen-123276. The changes that I made was that I upped each grain to 1 lb and added .25 lb of chocolate malt. I also used a different yeast that my brew shop recommended. –  anton2g Jun 25 '13 at 16:33
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@anton2g - thanks for the info - these kind of details would have been useful in your original question. I assumed dry yeast. If you can get hold of another smakpack with the same strain and can pitch within 24h then that's worth doing. 1 pack/100 billion cells is a serious underpitch, assuming a 5 gallon batch - mrmalty recommends 2.8 vials/smackpacks. –  mdma Jun 25 '13 at 17:04

If you used liquid yeast, you did not pitch enough yeast. Despite what the yeast manufacturers say, a pack of liquid yeast alone should not be used for a beer over 1.040 OG. Both my experience and scientific pitching rate calculators confirm this. If it was dry yeast, you probably have just barely enough. No matter which kind you used, it would be a good idea to add another pack of the same type at this point.

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Do I need to do anything special other than sterilizing the yeast bag and gently shaking it in after pouring it in? I have never pitched yeast after initial brew day. –  anton2g Jun 24 '13 at 19:07
    
No, considering your situation that will be fine. For info on pitching the proper amount of yeast in the future, see mrmalty.com . –  Denny Conn Jun 24 '13 at 19:20

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